At the end there will be a summary for those who like only particulars. In each topic I will bold the key sentences, so it will be easier to notice what’s the most important. Enjoy!
You can read about this headlamp here: https://flashlight.nitecore.com/Product/nu21
Or buy it here: Nitecore NU21 Headlamp Lightweight Rechargeable Headlamp
Table of Contents:
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General parameters
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Package content
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Appearance, parameters
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UI, runtime and charging
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PWM
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Waterproofness
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Light pattern, tint
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Beamshots
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Gallery and Summary
| Type | Description |
|---|---|
| Material | Plastic |
| Reflector | TIR |
| Lens | Plastic |
| Switch | Double e-switch |
| Brightness | 360lm max |
| Throw | 58m |
| Modes | 4 + strobe + beacon + constant red + beacon red |
| Max runtime | 37h |
| Mode memory | Yes |
| Battery | Built-in 500mAh Li-ion |
| Waterproof | IP66 |
| Impact resistance | 1m |
| Size | 53mm / 31mm / 23mm |
| Weight | Flashlight: - / Flashlight + battery: 44g |
Inside were:
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Headlamp
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USB C charging cable
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Manual
Nitecore NU21 is a very lightweight headlamp. Only 44g, in fact. This is less than a 18650 battery. It is crazy to think of it that way. You can have a whole headlamp with 3.5 hours of runtime (170lm, medium mode - plenty of light for an emergency situation, or…to be honest, most of the situations) instead of a single spare 18650 cell.
IF only it had a neutral 4000K - 4500K tint, maybe high CRI, this would be my mountain trip emergency light.
Anyway, let’s dive deeper:
In front there is a plastic lens with textured TIR optics to provide uniform-ish beam profile.
As we know, “glass is glass, and glass breaks”. On the other hand, glass scratches at level 3 with deeper grooves at level 4. But it is lighter. I can see why Nitecore decided to put plastic here. It is lightweight and won’t break when you accidentally slam your face into a tree. Understendable.
On top we have 2 buttons, which I honestly don’t know which one does what. I just click one of them randomly, and it works. As simple as that. Both buttons are designed to turn it on or off, and each of them has its unique functions as well.
The area that sticks to your greasy forehead is nice and soft. Nice touch from Nitecore, they could have left it to be just a plastic back. But someone decided that foreheads of Nitecore customers should get some love.
Hinge, or ATM - Advanced Tilting Mechanism is…really good. My first ever headlamp was Nitecore NU32 and it was…terrible. Sorry Nitecore, but you really put a disaster of a hinge here. IT TILTED LIKE CRAZY. It was unusable during a heavy rock gig. But with this headlamp you could be headbanging all day long and it would stay exactly where you left it.
The headband, my friends. Or headstring. One of the reasons it is so lightweight is because Nitecore uses as little stuff to keep it on the head as possible. More lightweight option would be to add a tube of super glue, but we might wait for NU22 for this invention.
On the other end of the headband is another ATM, this time an Advanced Tightening Mechanism. It lets you tighten it as much as you would like, so those small people (children) can wear it as well. No, really, it is good thing. This Nitecore NU21 might be your kid’s first real headlamp - not too bright, not that fragile, no glass, easy charging. Maybe one day your kid will have a collection of 100 different flashlights telling his wife it was $10 each, and all thanks to the NU21.
You can wear the headlamp on a lantern
And pretend it’s a police examining those three suspicious looking flashlights
Other, inpractical benefit of being able to tighten it so much is wearing it on your leg.
It could be very helpful for trips to the toilet at night. No more sudden obstacles. Your toes are saved now.
You can…wear it on your foot as well. Not sure why, but hey, you can. Can’t argue with that.
Other very useful use case would be to wear it on your hand. This way you could always have a handy light. Got it? 
See how useful that is?
UI
Two buttons to rule them all.
Navigation is simple, the headlamp can be turned on and off with both buttons. Nice feature is the ability to turn red light first, if you don’t want to blind yourself with the main white light.
Runtime
Heat dissipation
Whole case is plastic, and plastic is not good at heat dissipation. But don’t be fooled - it produces so little heat, the case material is not that important. 360lm max is not a lot of power and heat.
Charging
USB type C charging port, cable included. Rubber port cover is okay, fits tight, no complains here.
As described on the Nitecore website, it has no PWM
IP66
IP6X means maximum dust proof and IPX6 means maximum rain proof.
Cool light tint, max brightness 360 lumens. Unknown LED brand, as Nitecore said it is secret.
ISO200
t2s
f/3.5
5000K white balance
General picture of what the forest looks like:
Beamshots of Nitecore NU21:
Max brightness, aiming straight ahead (not the most practical use)
Max brightness, more realistic use. Plenty of light.
Red light is not bright, and it should not be bright.
This headlamp really needs no summary. It is lightweight, has a nice soft pad for your greasy forehead, the headband fits even very small heads, and you can charge it via USB C port.
And it’s cheap. I really like it, and as I said, if only it had warmer tint I would trust it to be my emergency mountain trip light.
Pros:
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Lightweight, only 44g
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Red light (constant + flashing)
Cons:
- Cool light tint
If you have any questions, put them below, thanks for sticking for a while 